Liquid crystal display device

ABSTRACT

The present invention provides an FFS mode liquid crystal display device that uses a liquid crystal composition which has a negative dielectric anisotropy and can achieve good display properties by being used for FFS mode liquid crystal display devices without degrading the image sticking property of display devices and various properties of liquid crystal display devices, such as dielectric anisotropy, viscosity, nematic phase upper limit temperature, low-temperature nematic phase stability, and γ1. The liquid crystal composition contains at least one compound selected from the group of compounds represented by general formula (I) below and at least one compound selected from the group of compounds represented by general formula (II) below.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.14/405,353, filed on Dec. 3, 2014, which is a 371 of InternationalApplication No. PCT/JP2013/076805, filed on Oct. 2, 2013, which claimsthe benefit of priority from the prior Japanese Patent Application No.2013-107929, filed on May 22, 2013, the entire contents of which areincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an FFS mode liquid crystal display thatuses a nematic liquid crystal composition having a negative dielectricanisotropy and that has a high transmittance and a high aperture ratio.

BACKGROUND ART

Active matrix liquid crystal display devices are commercially availableand used in, for example, portable terminals, liquid crystaltelevisions, projectors, and computers because of their high displayquality. In active matrix liquid crystal display devices, a TFT (thinfilm transistor), a MIM (metal-insulator-metal), or the like is used ineach pixel and a high voltage holding ratio is important for liquidcrystal compounds or liquid crystal compositions used in active matrixliquid crystal display devices. Liquid crystal display devices obtainedby combination with a VA (vertical alignment) mode, an IPS (in-planeswitching) mode, or an OCB (optically compensated bend or opticallycompensated birefringence) mode have been proposed to achieve goodvisual properties. Furthermore, ECB (electrically controlledbirefringence) mode reflective liquid crystal display devices have beenproposed to achieve brighter display. At present, novel liquid crystalcompounds or liquid crystal compositions are being proposed for suchliquid crystal display devices.

A fringe field switching (FFS) mode liquid crystal display, which is oneof IPS mode liquid crystal displays having high quality and good visualproperties, is being widely used as a liquid crystal display for smartphones (refer to PTL 1 and PTL 2). An FFS mode has been introduced toaddress the low aperture ratio and low transmittance of an IPS mode. Inan FFS mode, a material containing a p-type liquid crystal compositionhaving a positive dielectric anisotropy is widely used because thevoltage can be easily decreased. Since most of the application areas ofthe FFS mode are portable terminals, there is a high demand for lowerpower consumption and thus liquid crystal device manufacturers have beenactively making development efforts such as adoption of an array thatuses IGZO.

The transmittance can also be improved by changing a liquid crystalmaterial from a currently used p-type material to an n-type materialhaving a negative dielectric anisotropy (refer to PTL 3). The reason forthis is as follows. In the FFS mode, a completely parallel electricfield is not generated unlike the IPS mode. When a p-type material isused, the major axis of liquid crystal molecules located near a pixelelectrode is inclined along the fringing field, which degrades thetransmittance. In contrast, when an n-type liquid crystal composition isused, the influence of the fringing field is only on the rotation of theliquid crystal molecules about the major axis of the liquid crystalmolecules because the polarization direction of the n-type liquidcrystal composition is a minor-axis direction of the molecules. As aresult, the parallel arrangement of the molecule major axes ismaintained, and thus a decrease in the transmittance does not occur.

Although n-type liquid crystal compositions are typical liquid crystalcompositions for a VA mode, the VA mode and the FFS mode are differentfrom each other in terms of alignment direction, electric fielddirection, and required optical properties. Furthermore, FFS mode liquidcrystal display devices have a distinctive feature in terms of electrodestructure as described below. That is, both substrates include anelectrode in the VA mode whereas only an array substrate includes anelectrode in the FFS mode. Therefore, there is no knowledge aboutproblems such as image sticking and drop marks, which makes it difficultto predict the improvement from the related art. Accordingly, it isdifficult to provide a liquid crystal display device having the level ofhigh performance required today by simply using a liquid crystalcomposition for a VA mode, and therefore an n-type liquid crystalcomposition optimized for an FFS mode is desired.

CITATION LIST Patent Literature

PTL 1: Japanese Unexamined Patent Application Publication No. 11-202356

PTL 2: Japanese Unexamined Patent Application Publication No.2003-233083

PTL 3: Japanese Unexamined Patent Application Publication No. 2002-31812

SUMMARY OF INVENTION Technical Problem

It is an object of the present invention to provide a liquid crystaldisplay device that uses an n-type liquid crystal composition which isexcellent in terms of various properties for liquid crystal displaydevices, such as dielectric anisotropy (Δ∈), viscosity (η), nematicphase-isotropic liquid phase transition temperature (T_(NI)),low-temperature nematic phase stability, and rotational viscosity (γ₁),and which can achieve good display properties by being used for FFS modeliquid crystal display devices.

Solution to Problem

The inventors of the present invention have thoroughly conducted studiesto achieve the above object. As a result of studies on various liquidcrystal compositions which are most suitable for FFS mode liquid crystaldisplay devices, the inventors have found the effectiveness of a liquidcrystal composition containing two liquid crystal compounds each havinga distinctive structure and have completed the present invention.

The present invention provides a liquid crystal display device includinga first transparent insulating substrate and a second transparentinsulating substrate disposed so as to face each other; a liquid crystallayer containing a liquid crystal composition and sandwiched between thefirst substrate and the second substrate;

a common electrode composed of a transparent conductive material anddisposed on the first substrate; a plurality of gate bus lines and aplurality of data bus lines disposed on the first substrate so as toform a matrix;

a thin film transistor disposed at each of intersections of the gate buslines and the data bus lines; a pixel electrode composed of atransparent conductive material and driven by the transistor, the thinfilm transistor and the pixel electrode being included in each pixel;and

alignment films that induce homogeneous alignment and are disposedbetween the liquid crystal layer and the first substrate and between theliquid crystal layer and the second substrate, alignment directions ofthe alignment films being parallel to each other,

wherein an interelectrode distance R between the pixel electrode and thecommon electrode is smaller than a distance G between the firstsubstrate and the second substrate so that a fringing field is formedbetween the pixel electrode and the common electrode,

the common electrode is disposed on substantially an entire surface ofthe first substrate so as to be closer to the first substrate than thepixel electrode, and

the liquid crystal composition has a negative dielectric anisotropy, anematic phase-isotropic liquid phase transition temperature of 60° C. orhigher, and an absolute value of dielectric anisotropy of 2 or more andcontains at least one compound selected from the group of compoundsrepresented by general formula (I) below,

(in the formula, R¹ and R² each independently represent an alkyl grouphaving 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms,an alkoxy group having 1 to 8 carbon atoms, or an alkenyloxy grouphaving 2 to 8 carbon atoms; A represents a 1,4-phenylene group or atrans-1,4-cyclohexylene group; k represents 1 or 2; and when krepresents 2, two A may be the same or different) and at least onecompound selected from the group of compounds represented by generalformula (II) below,

(in the formula, R³ represents an alkyl group having 1 to 8 carbonatoms, an alkenyl group having 2 to 8 carbon atoms, an alkoxy grouphaving 1 to 8 carbon atoms, or an alkenyloxy group having 2 to 8 carbonatoms; R⁴ represents an alkyl group having 1 to 8 carbon atoms, analkenyl group having 4 to 8 carbon atoms, an alkoxy group having 1 to 8carbon atoms, or an alkenyloxy group having 3 to 8 carbon atoms; Brepresents a 1,4-phenylene group or a trans-1,4-cyclohexylene group; mrepresents 0, 1, or 2; and when m represents 2, two B may be the same ordifferent).

Advantageous Effects of Invention

The FFS mode liquid crystal display device according to the presentinvention has high-speed response, hardly causes display defects, andexhibits good display properties. The liquid crystal display deviceaccording to the present invention is useful for display devices such asliquid crystal TVs and monitors.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 schematically shows an example of a structure of a liquid crystaldisplay device of the present invention.

FIG. 2 is an enlarged plan view of a region of an electrode layer 3formed on a in FIG. 1, the region being enclosed by line II.

FIG. 3 is a sectional view of the liquid crystal display device shown inFIG. 1, the sectional view being taken along line III-III in FIG. 2.

FIG. 4 schematically shows a liquid crystal alignment direction inducedby alignment films 4.

FIG. 5 shows another example of an enlarged plan view of a region of anelectrode layer 3 formed on a substrate 2 in FIG. 1, the region beingenclosed by line II.

FIG. 6 shows another example of a sectional view of the liquid crystaldisplay device shown in FIG. 1, the sectional view being taken alongline III-III in FIG. 2.

DESCRIPTION OF EMBODIMENTS

As described above, the present invention is made by finding an n-typeliquid crystal composition which is most suitable for FFS mode liquidcrystal display devices. An embodiment of the liquid crystal compositionaccording to the present invention will be described below.

(Liquid Crystal Layer)

The liquid crystal composition according to the present inventioncontains one or more of compounds represented by general formula (I) asfirst components.

(In the formula, R¹ and R² each independently represent an alkyl grouphaving 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms,an alkoxy group having 1 to 8 carbon atoms, or an alkenyloxy grouphaving 2 to 8 carbon atoms; A represents a 1,4-phenylene group or atrans-1,4-cyclohexylene group; k represents 1 or 2; and when krepresents 2, two A may be the same or different.)

The lower limit of the total content of the compounds represented by thegeneral formula (I) in the entire composition is preferably 5 mass %,more preferably 10 mass %, more preferably 15 mass %, particularlypreferably 20 mass %, and most preferably 25 mass %. The upper limit ofthe total content is preferably 65 mass %, more preferably 55 mass %,more preferably 50 mass %, particularly preferably 47 mass %, and mostpreferably 45 mass %.

For example, the compounds represented by the general formula (I) arespecifically compounds represented by general formula (I-a) to generalformula (I-e) below.

(In the formulae, R¹¹ to R¹⁵ and R²¹ to R²⁵ each independently representan alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or analkenyloxy group having 2 to 8 carbon atoms.)

One to ten of compounds selected from the group of the compoundsrepresented by the general formula (I-a) to the general formula (I-e)are preferably contained, one to eight of the compounds are morepreferably contained, and one to five of the compounds are particularlypreferably contained. Two or more of the compounds are also preferablycontained.

Preferably, R¹¹ to R¹⁵ and R²¹ to R²⁵ each independently represent analkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8carbon atoms, or an alkoxy group having 2 to 8 carbon atoms. Morepreferably, R¹¹ to R¹⁵ and R²¹ to R²⁵ each independently represent analkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5carbon atoms, or an alkoxy group having 2 to 5 carbon atoms. When R¹¹ toR¹⁵ and R²¹ to R²⁵ represent an alkenyl group, the alkenyl grouppreferably has structures represented by formula (i) to formula (iv)below.

(In the formulae, the right terminal bonds to a ring structure.)

R¹¹ and R²¹, R¹² and R²², R¹³ and R²³, R¹⁴ and R²⁴, and R¹⁵ and R²⁵ maybe the same or different, but preferably represent differentsubstituents.

From this viewpoint, for example, the compounds represented by thegeneral formula (I) preferably include at least one compound selectedfrom the group of compounds represented by general formula (III) below.

(In the formula, R⁵ represents a hydrogen atom or a methyl group and R⁶represents an alkyl group having 1 to 5 carbon atoms, an alkenyl grouphaving 2 to 5 carbon atoms, or an alkoxy group having 1 to 4 carbonatoms.)

More specifically, the compounds represented by the general formula(III) are preferably the following compounds.

When the compounds represented by the general formula (III) arecontained, the lower limit of the content of the compounds representedby the general formula (III) in the liquid crystal composition ispreferably 5 mass %, more preferably 15 mass %, more preferably 20 mass%, particularly preferably 23 mass %, and most preferably 25 mass %. Theupper limit of the content is preferably 70 mass %, more preferably 60mass %, more preferably 55 mass %, particularly preferably 52 mass %,and most preferably 50 mass %. More specifically, when an importance isgiven to response speed, the lower limit is preferably 20 mass %, morepreferably 30 mass %, more preferably 35 mass %, particularly preferably38 mass %, and most preferably 35 mass %. The upper limit is preferably70 mass %, more preferably 60 mass %, more preferably 55 mass %,particularly preferably 52 mass %, and most preferably 50 mass %. Whenan importance is given to drive voltage, the lower limit is preferably 5mass %, more preferably 15 mass %, more preferably 20 mass %,particularly preferably 23 mass %, and most preferably 25 mass %. Theupper limit is preferably 60 mass %, more preferably 50 mass %, morepreferably 45 mass %, particularly preferably 42 mass %, and mostpreferably 40 mass %. The lower limit of the ratio of the content of thecompounds represented by the general formula (III) to the total contentof the compounds represented by the general formula (I) in the liquidcrystal composition is preferably 60 mass %, more preferably 70 mass %,more preferably 75 mass %, particularly preferably 78 mass %, and mostpreferably 80 mass %. The upper limit of the ratio is preferably 90 mass%, more preferably 95 mass %, more preferably 97 mass %, particularlypreferably 99 mass %, and preferably 100 mass %.

More specifically, the compounds represented by the general formula(I-a) to the general formula (I-e) other than the compounds representedby the general formula (III) are preferably the following compounds.

Among them, the compounds represented by formula (III-a2), formula(III-b2), formula (I-a1) to formula (I-a6), formula (I-b2), formula(I-b6), formula (I-d1), formula (I-d2), formula (I-d3), and formula(I-e2) are preferred.

The liquid crystal composition according to the present inventioncontains one or more of compounds represented by general formula (II) assecond components.

(In the formula, R³ represents an alkyl group having 1 to 8 carbonatoms, an alkenyl group having 2 to 8 carbon atoms, an alkoxy grouphaving 1 to 8 carbon atoms, or an alkenyloxy group having 2 to 8 carbonatoms; R⁴ represents an alkyl group having 1 to 8 carbon atoms, analkenyl group having 4 to 8 carbon atoms, an alkoxy group having 1 to 8carbon atoms, or an alkenyloxy group having 3 to 8 carbon atoms; Brepresents a 1,4-phenylene group or a trans-1,4-cyclohexylene group; mrepresents 0, 1, or 2; and when m represents 2, two B may be the same ordifferent.)

The lower limit of the content of the compounds represented by thegeneral formula (II) in the liquid crystal composition is preferably 10mass %, more preferably 20 mass %, more preferably 25 mass %,particularly preferably 28 mass %, and most preferably 30 mass %. Theupper limit of the content is preferably 85 mass %, more preferably 75mass %, more preferably 70 mass %, particularly preferably 67 mass %,and most preferably 65 mass %.

The compounds represented by the general formula (II) are preferably oneor more compounds selected from the group of compounds represented bygeneral formula (IIa) to general formula (IIc) and more preferably twoor more compounds selected from the group of compounds represented bygeneral formula (IIa) to general formula (IIc).

(In the formulae, R³¹ to R³³ and R⁴¹ to R⁴³ represent the same meaningas R³ and R⁴ in the general formula (II).)

Specifically, the compounds represented by the general formula (IIa) arepreferably compounds represented by formula (IIa-1) to formula (IIa-8).

The compounds represented by the general formula (IIa) are morepreferably compounds represented by formula (IIa-1) to formula (IIa-4)and further preferably compounds represented by formula (IIa-1) andformula (IIa-3).

The lower limit of the content of the compounds represented by thegeneral formula (IIa) is preferably 2 mass % and more preferably 3 mass%, and the upper limit of the content is preferably 45 mass %, morepreferably 35 mass %, more preferably 30 mass %, particularly preferably27 mass %, and most preferably 25 mass %.

When four or more of the compounds represented by the general formula(IIa) are used, the compounds represented by the formula (IIa-1) to theformula (IIa-4) are preferably used in combination and the content ofthe compounds represented by the formula (IIa-1) to the formula (IIa-4)in the compounds represented by the general formula (IIa) is preferably50 mass % or more, more preferably 70 mass % or more, and furtherpreferably 80 mass % or more.

When three of the compounds represented by the general formula (IIa) areused, the compounds represented by the formula (IIa-1), the formula(IIa-2), and the formula (IIa-3) are preferably used in combination andthe content of the compounds represented by the formula (IIa-1), theformula (IIa-2), and the formula (IIa-3) in the compounds represented bythe general formula (IIa) is preferably 50 mass % or more, morepreferably 70 mass % or more, more preferably 80 mass % or more,particularly preferably 85 mass % or more, and most preferably 90 mass %or more.

When two of the compounds represented by the general formula (IIa) areused, the compounds represented by the formula (IIa-1) and the formula(IIa-3) are preferably used in combination and the content of thecompounds represented by the formula (IIa-1) and the formula (IIa-3) inthe compounds represented by the general formula (IIa) is preferably 50mass % or more, more preferably 70 mass % or more, more preferably 80mass % or more, particularly preferably 85 mass % or more, and mostpreferably 90 mass % or more.

Specifically, the compounds represented by the general formula (IIb) arepreferably compounds represented by formula (IIb-1) to formula (IIb-6)below.

The compounds represented by the general formula (IIb) are morepreferably compounds represented by formula (IIb-1) to formula (IIb-4),further preferably compounds represented by formula (IIb-1) to formula(IIb-3), and particularly preferably compounds represented by formula(IIb-1) and formula (IIb-3).

When four or more of the compounds represented by the general formula(IIb) are used, the compounds represented by the formula (IIb-1) to theformula (IIb-4) are preferably used in combination and the content ofthe compounds represented by the formula (IIb-1) to the formula (IIb-4)in the compounds represented by the general formula (IIb) is preferably50 mass % or more, more preferably 70 mass % or more, more preferably 80mass % or more, particularly preferably 85 mass % or more, and mostpreferably 90 mass % or more.

When three of the compounds represented by the general formula (IIb) areused, the compounds represented by the formula (IIb-1) to the formula(IIb-3) are preferably used in combination and the content of thecompounds represented by the formula (IIb-1) to the formula (IIb-3) inthe compounds represented by the general formula (IIb) is preferably 50mass % or more, more preferably 70 mass % or more, more preferably 80mass % or more, particularly preferably 85 mass % or more, and mostpreferably 90 mass % or more.

When two of the compounds represented by the general formula (IIb) areused, the compounds represented by the formula (IIb-1) and the formula(IIb-3) are preferably used in combination and the content of thecompounds represented by the formula (IIb-1) and the formula (IIb-3) inthe compounds represented by the general formula (IIb) is preferably 50mass % or more, more preferably 70 mass % or more, more preferably 80mass % or more, particularly preferably 85 mass % or more, and mostpreferably 90 mass % or more.

Specifically, the compounds represented by the general formula (IIc) arepreferably compounds represented by formula (IIc-1) to formula (IIc-4).

The compounds represented by the general formula (IIc) are morepreferably compounds represented by formula (IIc-1) and formula (IIc-2).

When two or more of the compounds represented by the general formula(IIc) are used, the compounds represented by the formula (IIc-1) and theformula (IIc-2) are preferably used in combination and the content ofthe compounds represented by the formula (IIc-1) and the formula (IIc-2)in the compounds represented by the general formula (IIc) is preferably50 mass % or more, more preferably 70 mass % or more, more preferably 80mass % or more, particularly preferably 85 mass % or more, and mostpreferably 90 mass % or more.

The composition according to the present invention preferably furthercontains compounds represented by general formula (IV). Note that thecompounds represented by the general formula (IV) exclude the compoundsrepresented by the general formula (II).

(In the formula, R⁷ and R⁸ each independently represent an alkyl grouphaving 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms,an alkoxy group having 1 to 8 carbon atoms, or an alkenyloxy grouphaving 2 to 8 carbon atoms; one or more hydrogen atoms in the alkylgroup, the alkenyl group, the alkoxy group, or the alkenyloxy group maybe substituted with fluorine atoms; a methylene group in the alkylgroup, the alkenyl group, the alkoxy group, or the alkenyloxy group maybe substituted with an oxygen atom as long as oxygen atoms do notdirectly bond to each other and may be substituted with a carbonyl groupas long as carbonyl groups do not directly bond to each other;A¹ and A² each independently represent a 1,4-cyclohexylene group, a1,4-phenylene group, or a tetrahydropyran-2,5-diyl group; when A¹ and/orA² represents a 1,4-phenylene group, one or more hydrogen atoms in the1,4-phenylene group may be substituted with fluorine atoms;Z¹ and Z² each independently represent a single bond, —OCH₂—, —OCF₂—,—CH₂O—, or CF₂O—; n¹ and n² each independently represent 0, 1, 2, or 3and n¹+n² is 1 to 3; when a plurality of A¹, A², Z¹, and/or Z² arepresent, A¹, A², Z¹, and/or Z² may be the same or different; and acompound in which n¹ represents 1 or 2, n² represents 0, at least one ofA¹ represents a 1,4-cyclohexylene group, and all Z¹ are single bonds isexcluded.)

The lower limit of the content of the compounds represented by thegeneral formula (IV) in the liquid crystal composition is preferably 2mass %, more preferably 3 mass %, more preferably 4 mass %, andparticularly preferably 5 mass %. The upper limit of the content ispreferably 45 mass %, more preferably 35 mass %, more preferably 30 mass%, particularly preferably 27 mass %, and most preferably 25 mass %.

In the general formula (IV), R⁷ and R⁸ preferably represent an alkylgroup or an alkenyl group when a ring structure to which each of R⁷ andR⁸ bonds is cyclohexane or tetrahydropyran and preferably represent analkyl group, an alkoxy group, or an alkenyl group when a ring structureto which each of R⁷ and R⁸ bonds is benzene. When the ring structure towhich each of R⁷ and R⁸ bonds is cyclohexane or tetrahydropyran, R⁷ andR⁸ preferably represent an alkyl group having 1 to 8 carbon atoms or analkenyl group having 2 to 8 carbon atoms, more preferably represent analkyl group having 1 to 8 carbon atoms, more preferably represent analkyl group having 3 to 5 carbon atoms, more preferably represent analkyl group having 3 or 5 carbon atoms, and preferably represent alinear group. In the general formula (IV), when the ring structure towhich each of R⁷ and R⁸ bonds is benzene, R⁷ and R⁸ preferably representan alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or analkenyloxy group having 2 to 8 carbon atoms, more preferably representan alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to8 carbon atoms, more preferably represent an alkyl group having 3 to 5carbon atoms or an alkoxy group having 2 to 4 carbon atoms, morepreferably represent an alkyl group having 3 or 5 carbon atoms or analkoxy group having 2 or 4 carbon atoms, more preferably represent analkoxy group having 2 or 4 carbon atoms, and preferably represent alinear group.

When an importance is given to an improvement in the response speed of adisplay device, an alkenyl group is preferred. When an importance isgiven to reliability such as a voltage holding ratio or the like, analkyl group is preferred. The alkenyl group preferably has structuresrepresented by formula (i) to formula (iv) below.

(In the formulae, the right terminal bonds to the ring structure.)

A¹ and A² preferably each independently represent a 1,4-cyclohexylenegroup, a 1,4-phenylene group, or a tetrahydropyran-2,5-diyl group.

When an importance is given to a decrease in viscosity, Z¹ and Z²preferably each independently represent a single bond. When animportance is given to an increase in the absolute value of Δ∈, Z¹ andZ² preferably each independently represent —OCH₂—, —OCF₂—, —CH₂O—, or—CF₂O— and an oxygen atom is preferably configured so as to bond to a2,3-difluorobenzene-1,4-diyl group.

Preferably, n¹+n² is 2 or less. When an importance is given to adecrease in viscosity, n¹+n² is preferably 1. When an importance isgiven to T_(ni) or an increase in Δn, n¹+n² is preferably 2.

The compounds represented by the general formula (IV) are preferablyselected from the group of compounds represented by general formulae(IVa1) and (IVa2) below.

(In the formulae, R^(7a1), R^(7a2), R^(8a1), and R^(8a2) eachindependently represent an alkyl group having 1 to 8 carbon atoms, analkenyl group having 2 to 8 carbon atoms, an alkoxy group having 1 to 8carbon atoms, or an alkenyloxy group having 2 to 8 carbon atoms; one ormore hydrogen atoms in the alkyl group, the alkenyl group, the alkoxygroup, or the alkenyloxy group may be substituted with fluorine atoms; amethylene group in the alkyl group, the alkenyl group, the alkoxy group,or the alkenyloxy group may be substituted with an oxygen atom as longas oxygen atoms do not directly bond to each other and may besubstituted with a carbonyl group as long as carbonyl groups do notdirectly bond to each other;n^(a2) represents 0 or 1; A^(1a2) represents a 1,4-cyclohexylene group,a 1,4-phenylene group, or a tetrahydropyran-2,5-diyl group; and one ormore hydrogen atoms in the 1,4-phenylene group in the general formula(IVa1) and the general formula (IVa2) may be substituted with fluorineatoms.)

Specifically, the compounds represented by the general formula (IVa1)are preferably compounds represented by formula (IVa1-1) to formula(IVa1-8).

The compounds represented by the general formula (IVa1) are morepreferably compounds represented by formula (IVa1-1) to formula(IVa1-4), further preferably compounds represented by formula (IVa1-1)and formula (IVa1-3), and particularly preferably a compound representedby formula (IVa1-1).

When four or more of the compounds represented by the general formula(IVa1) are used, the compounds represented by the formula (IVa1-1) tothe formula (IVa1-4) are preferably used in combination and the contentof the compounds represented by the formula (IVa1-1) to the formula(IVa1-4) in the compounds represented by the general formula (IVa1) ispreferably 50 mass % or more, more preferably 70 mass % or more, morepreferably 80 mass % or more, particularly preferably 85 mass % or more,and most preferably 90 mass % or more.

When three of the compounds represented by the general formula (IVa1)are used, the compounds represented by the formula (IVa1-1) to theformula (IVa1-3) are preferably used in combination and the content ofthe compounds represented by the formula (IVa1-1) to the formula(IVa1-3) in the compounds represented by the general formula (IVa1) ispreferably 50 mass % or more, more preferably 70 mass % or more, morepreferably 80 mass % or more, particularly preferably 85 mass % or more,and most preferably 90 mass % or more.

When two of the compounds represented by the general formula (IVa1) areused, the compounds represented by the formula (IVa1-1) and the formula(IVa1-3) are preferably used in combination and the content of thecompounds represented by the formula (IVa1-1) and the formula (IVa1-3)in the compounds represented by the general formula (IVa1) is preferably50 mass % or more, more preferably 70 mass % or more, more preferably 80mass % or more, particularly preferably 85 mass % or more, and mostpreferably 90 mass % or more.

The compounds represented by the general formula (IVa2) are preferablycompounds represented by general formula (IVa2-1) to general formula(IVa2-9).

(In the formulae, R⁷ represents the same meaning as R⁷ in the generalformula (IV) and R⁸ represents the same meaning as R⁸ in the generalformula (IV).)

When the compounds represented by the general formula (IVa2) are used,the compound represented by the formula (IVa2-1) is preferably used. Thecontent of the compound represented by the formula (IVa2-1) in thecompounds represented by the general formula (IVa2) is preferably 50mass % or more, more preferably 70 mass % or more, more preferably 80mass % or more, particularly preferably 85 mass % or more, and mostpreferably 90 mass % or more.

In the general formula (IVa2), R⁷ and R⁸ each independently represent analkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or analkenyloxy group having 2 to 8 carbon atoms, preferably eachindependently represent an alkyl group having 1 to 8 carbon atoms or analkenyl group having 2 to 8 carbon atoms, more preferably eachindependently represent an alkyl group having 2 to 5 carbon atoms or analkenyl group having 2 to 5 carbon atoms, more preferably each representan alkyl group having 2 or 5 carbon atoms, and preferably each representa linear group. When R⁷ and R⁸ each represent an alkyl group, thenumbers of carbon atoms in R⁷ and R⁸ are preferably different from eachother.

More specifically, a compound with R⁷ representing a propyl group and R⁸representing an ethyl group or a compound with R⁷ representing a butylgroup and R⁸ representing an ethyl group is preferred.

The 1,4-cyclohexyl group in the present invention is preferably atrans-1,4-cyclohexyl group.

The liquid crystal composition according to the present inventioncontains the compounds represented by the general formula (I) and thegeneral formula (II) as essential components and may further contain thecompounds represented by the general formula (IV) (which exclude thecompounds represented by the general formula (II)). The total content ofthe compounds represented by the general formula (I), the generalformula (II), and the general formula (IV) in the liquid crystalcomposition is preferably 80 to 100 mass %, more preferably 85 to 100mass %, more preferably 90 to 100 mass %, particularly preferably 95 to100 mass %, and most preferably 97 to 100 mass %.

The lower limit of the total content of the compounds represented by thegeneral formula (I) and the general formula (II) in the liquid crystalcomposition of the present invention is preferably 55 mass %, morepreferably 65 mass %, more preferably 70 mass %, particularly preferably73 mass %, and most preferably 75 mass %. The upper limit of the totalcontent is preferably 85 mass %, more preferably 90 mass %, morepreferably 92 mass %, particularly preferably 94 mass %, and mostpreferably 95 mass %.

The liquid crystal composition according to the present inventionpreferably does not contain a compound having a structure in whichoxygen atoms bond to each other, such as a peracid (—CO—OO—) structure,in its molecule.

When an importance is given to the reliability and long-term stabilityof the liquid crystal composition, the content of a compound having acarbonyl group is preferably 5 mass % or less, more preferably 3 mass %or less, and more preferably 1 mass % or less relative to the total massof the composition. Most preferably, the liquid crystal compositionsubstantially does not contain the compound having a carbonyl group.

The content of a compound in which all the intramolecular ringstructures are six-membered rings is preferably increased. The contentof the compound in which all the intramolecular ring structures aresix-membered rings is preferably 80 mass % or more, more preferably 90mass % or more, and more preferably 95 mass % or more relative to thetotal mass of the composition. Most preferably, the liquid crystalcomposition is substantially constituted by only compounds in which allthe intramolecular ring structures are six-membered rings.

To suppress the degradation of the liquid crystal composition due tooxidation, the content of a compound having a cyclohexenylene group as aring structure is preferably decreased. The content of the compoundhaving a cyclohexenylene group is preferably 10 mass % or less and morepreferably 5 mass % or less relative to the total mass of thecomposition. More preferably, the liquid crystal compositionsubstantially does not contain the compound having a cyclohexenylenegroup.

To suppress the degradation of the liquid crystal composition due tooxidation, the content of a compound having —CH═CH— as a linking groupis preferably decreased. The content of the compound is preferably 10mass % or less and more preferably 5 mass % or less relative to thetotal mass of the composition. More preferably, the liquid crystalcomposition substantially does not contain the compound.

When an importance is given to the improvement in viscosity and T_(NI),the content of a compound intramolecularly having a2-methylbenzene-1,4-diyl group whose hydrogen atoms may be substitutedwith halogens is preferably decreased. The content of the compoundintramolecularly having the 2-methylbenzene-1,4-diyl group is preferably10 mass % or less and more preferably 5 mass % or less relative to thetotal mass of the composition. More preferably, the liquid crystalcomposition substantially does not contain the compound intramolecularlyhaving a 2-methylbenzene-1,4-diyl group.

In the case where the compounds contained in the composition accordingto the present invention have an alkenyl group as a side chain, when thealkenyl group bonds to cyclohexane, the number of carbon atoms in thealkenyl group is preferably 2 to 5. When the alkenyl group bonds tobenzene, the number of carbon atoms in the alkenyl group is preferably 4or 5. The unsaturated bond of the alkenyl group is preferably notdirectly bonded to benzene. When an importance is given to the stabilityof the liquid crystal composition, the content of a compound having analkenyl group as a side chain and having a 2,3-difluorobenzene-1,4-diylgroup is preferably decreased. The content of the compound is preferably10 mass % or less and more preferably 5 mass % or less relative to thetotal mass of the composition. More preferably, the liquid crystalcomposition substantially does not contain the compound.

The liquid crystal composition according to the present invention has anegative dielectric anisotropy Δ∈, and the absolute value of thedielectric anisotropy is 2 or more. The dielectric anisotropy Δ∈ at 25°C. is preferably −2.0 to −6.0, more preferably −2.5 to −5.0, andparticularly preferably −2.5 to −4.0. More specifically, when animportance is given to response speed, the dielectric anisotropy Δ∈ ispreferably −2.5 to −3.4. When an importance is given to drive voltage,the dielectric anisotropy Δ∈ is preferably −3.4 to −4.0.

The refractive index anisotropy Δn of the liquid crystal compositionaccording to the present invention at 25° C. is preferably 0.08 to 0.13and more preferably 0.09 to 0.12. More specifically, the refractiveindex anisotropy Δn is preferably 0.10 to 0.12 for a small cell gap and0.08 to 0.10 for a large cell gap.

The rotational viscosity (γ₁) of the liquid crystal compositionaccording to the present invention is preferably 150 or less, morepreferably 130 or less, and particularly preferably 120 or less.

In the liquid crystal composition according to the present invention, Z,which is a function of rotational viscosity and refractive indexanisotropy, preferably has a particular value.

Z=γ1/Δn ²  [Math. 1]

(In the formula, γ₁ represents a rotational viscosity and Δn representsa refractive index anisotropy.)

Z is preferably 13000 or less, more preferably 12000 or less, andparticularly preferably 11000 or less.

The nematic phase-isotropic liquid phase transition temperature (T_(ni))of the liquid crystal composition according to the present invention is60° C. or higher, preferably 75° C. or higher, more preferably 80° C. orhigher, and more preferably 90° C. or higher.

The liquid crystal composition according to the present invention needsto have a specific resistance of 10¹² (Ω·m) or more, and the specificresistance is preferably 10¹³ (Ω·m) and more preferably 10¹⁴ (Ω·m) ormore.

In addition to the above compounds, the liquid crystal compositionaccording to the present invention may further contain a typical nematicliquid crystal, a smectic liquid crystal, a cholesteric liquid crystal,an antioxidant, an ultraviolet absorber, and the like in accordance withthe application. When chemical stability is required for the liquidcrystal composition, the liquid crystal composition preferably does notinclude chlorine atoms in its molecule. When stability for light such asultraviolet light is required for the liquid crystal composition, theliquid crystal composition desirably does not intramolecularly includecondensed rings or the like that have a large conjugation length and anabsorption peak in an ultraviolet region, such as a naphthalene ring.

(Liquid Crystal Display Device)

The above-described liquid crystal composition according to the presentinvention is applied to an FFS mode liquid crystal display device.Hereafter, an example of the FFS mode liquid crystal display deviceaccording to the present invention will be described with reference toFIGS. 1 to 6.

FIG. 1 schematically shows a structure of a liquid crystal displaydevice. In FIG. 1, components are illustrated in a separated manner forease of description. As shown in FIG. 1, a liquid crystal display device10 according to the present invention is an FFS mode liquid crystaldisplay device including a liquid crystal composition (or a liquidcrystal layer 5) sandwiched between a first transparent insulatingsubstrate 2 and a second transparent insulating substrate 7 disposed soas to face each other, the liquid crystal composition being the liquidcrystal composition according to the present invention. An electrodelayer 3 is formed on a surface of the first transparent insulatingsubstrate 2 on the liquid crystal layer 5 side. A pair of alignmentfilms 4 that are directly in contact with the liquid crystal compositionconstituting the liquid crystal layer 5 and induce homogeneous alignmentare disposed between the liquid crystal layer 5 and the firsttransparent insulating substrate 2 and between the liquid crystal layer5 and the second transparent insulating substrate 8. Liquid crystalmolecules in the liquid crystal composition are aligned so as to besubstantially parallel to the substrates 2 and 7 when no voltage isapplied. As shown in FIGS. 1 and 3, the second substrate 2 and the firstsubstrate 8 may be sandwiched between a pair of polarizing plates 1 and8. In FIG. 1, a color filter 6 is further disposed between the secondsubstrate 7 and the alignment film 4.

In short, the liquid crystal display device 10 according to the presentinvention includes the first polarizing plate 1, the first substrate 2,the electrode layer 3 including a thin film transistor, the alignmentfilm 4, the liquid crystal layer 5 containing the liquid crystalcomposition, the alignment film 4, the color filter 6, the secondsubstrate 7, and the second polarizing plate 8 which are sequentiallystacked. The first substrate 2 and the second substrate 7 can becomposed of glass or a transparent flexible material such as plastic,and one of the first substrate 2 and the second substrate 7 may becomposed of an opaque material such as silicon. The substrates 2 and 7are bonded to each other with a sealing material or a sealant, such asan epoxy thermosetting composition, disposed in a peripheral region. Forexample, particulate spacers such as glass particles, plastic particles,or alumina particles or columnar spacers composed of a resin and formedby photolithography may be disposed between the substrates 2 and 7 inorder to keep the distance between the substrates 2 and 7.

FIG. 2 is an enlarged plan view of a region of the electrode layer 3formed on the substrate 2 in FIG. 1, the region being enclosed by lineII. FIG. 3 is a sectional view of the liquid crystal display deviceshown in FIG. 1, the sectional view being taken along line III-III inFIG. 2. As shown in FIG. 2, the electrode layer 3 including a thin filmtransistor and formed on the surface of the first substrate 2 includes aplurality of gate bus lines 26 for supplying scanning signals and aplurality of data bus lines 25 for supplying display signals, the gatebus lines 26 and the data bus lines 25 intersecting each other so as toform a matrix. FIG. 2 shows only a pair of gate bus lines 25 and a pairof data bus lines 24.

A unit pixel of the liquid crystal display is formed in each of regionssurrounded by the plurality of gate bus lines 26 and the plurality ofdata bus lines 25. In the unit pixel, a pixel electrode 21 and a commonelectrode 22 are formed. A thin film transistor including a sourceelectrode 27, a drain electrode 24, and a gate electrode 28 is disposednear each of intersections of the gate bus lines 26 and the data buslines 25. The thin film transistor is connected to the pixel electrode21 as a switching element for supplying display signals to the pixelelectrode 21. Furthermore, a common line 29 is disposed so as to beparallel to the gate bus lines 26. The common line 29 is connected tothe common electrode 22 to supply common signals to the common electrode22.

As shown in FIG. 3, a thin film transistor according to a preferredembodiment includes a gate electrode 11 formed on a surface of asubstrate 2, a gate insulating layer 12 disposed so as to cover the gateelectrode 11 and substantially the entire surface of the substrate 2, asemiconductor layer 13 formed on a surface of the gate insulating layer12 so as to face the gate electrode 11, a protective film 14 disposed soas to cover part of a surface of the semiconductor layer 17, a drainelectrode 16 disposed so as to cover one-side portions of the protectivefilm 14 and the semiconductor layer 13 and so as to be in contact withthe gate insulating layer 12 formed on the surface of the substrate 2, asource electrode 17 disposed so as to cover the other-side portions ofthe protective film 14 and the semiconductor layer 13 and so as to be incontact with the gate insulating layer 12 formed on the surface of thesubstrate 2, and an insulating protective layer 18 disposed so as tocover the drain electrode 16 and the source electrode 17. An anodicoxide film (not shown) may be formed on a surface of the gate electrode11 for the purpose of, for example, removing a difference in levelformed by the gate electrode.

The semiconductor layer 13 may be composed of amorphous silicon,polycrystalline polysilicon, or the like. The semiconductor layer 13 ispreferably a transparent semiconductor film composed of, for example,ZnO, IGZO (In—Ga—Zn—O), or ITO because harmful effects of photocarriersdue to light absorption can be suppressed and the aperture ratio of adevice can be increased.

An ohmic contact layer 15 may be disposed between the semiconductorlayer 13 and the drain electrode 16 or the source electrode 17 in orderto decrease the width and height of a Schottky barrier. The ohmiccontact layer may be composed of a material to which an impurity such asphosphorus is added in a high concentration. Examples of the materialinclude an n-type amorphous silicon and an n-type polycrystallinepolysilicon.

The gate bus lines 26, the data bus lines 25, and the common line 29 arepreferably metal films. The metal films are preferably composed of Al,Cu, Au, Ag, Cr, Ta, Ti, Mo, W, Ni, or an alloy thereof and morepreferably Al or an Al alloy. The insulating protective layer 18 is alayer having an insulating function and is formed of silicon nitride,silicon dioxide, or silicon oxynitride.

In the embodiment shown in FIGS. 2 and 3, the common electrode 22 is aplate-shaped electrode formed on substantially the entire surface of thegate insulating layer 12 whereas the pixel electrode 21 is a comb-shapedelectrode formed on the insulating protective layer 18 that covers thecommon electrode 22. In other words, the common electrode 22 is disposedso as to be closer to the first substrate 2 than the pixel electrode 21,and these electrodes overlap each other with the insulating protectivelayer 18 disposed therebetween. The pixel electrode 21 and the commonelectrode 22 are formed of a transparent conductive material such as ITO(indium tin oxide), IZO (indium zinc oxide), or IZTO (indium zinc tinoxide). Since the pixel electrode 21 and the common electrode 22 areformed of a transparent conductive material, the opening area in a unitpixel is increased, which increases the aperture ratio and thetransmittance.

Since a fringing field is formed between the pixel electrode 21 and thecommon electrode 22, the pixel electrode 21 and the common electrode 22are formed so that the interelectrode distance R between the pixelelectrode 21 and the common electrode 22 is smaller than the distance Gbetween the first substrate 2 and the second substrate 7. Note that theinterelectrode distance R indicates a distance between the electrodes ina direction horizontal to the substrates. FIG. 3 shows an example inwhich the interelectrode distance R is 0 because the plate-shaped commonelectrode 22 and the comb-shaped pixel electrode 21 overlap each other.The interelectrode distance R is smaller than the distance (cell gap) Gbetween the first substrate 2 and the second substrate 7, and thereforethe fringing field E is formed. Thus, in an FFS mode liquid crystaldisplay device, a horizontal electric field formed in a directionperpendicular to lines that form a comb-like shape of the pixelelectrode 21 and a parabolic electric field can be used. The electrodewidth 1 of a comb teeth portion of the pixel electrode 21 and the widthm of a gap between comb teeth portions of the pixel electrode 21 arepreferably set in such a manner that all liquid crystal molecules in theliquid crystal layer 5 are driven by the generated electric field.

In the color filter 6, a black matrix (not shown) is preferably formedin regions corresponding to the thin film transistor and a storagecapacitor 23 in order to prevent the leakage of light.

A pair of alignment films 4 that induce homogeneous alignment aredisposed on the electrode layer 3 and the color filter 6 so as to bedirectly in contact with the liquid crystal composition constituting theliquid crystal layer 5. The alignment films 4 are, for example,polyimide films subjected to a rubbing treatment, and the alignmentdirections of the alignment films are parallel to each other. A rubbingdirection (alignment direction of liquid crystal composition) of thealignment films 4 according to this embodiment will be described withreference to FIG. 4. FIG. 4 schematically shows a liquid crystalalignment direction induced by the alignment films 4. In the presentinvention, a liquid crystal composition having a negative dielectricanisotropy is used. Therefore, when the direction (direction in which anhorizontal electric field is formed) perpendicular to lines that form acomb-like shape of the pixel electrode 21 is assumed to be an x-axisdirection, liquid crystal molecules 30 are preferably aligned so thatthe angle θ between the x-axis direction and a major-axis direction ofeach liquid crystal molecule 30 is about 0° to 45°. FIG. 3 shows anexample in which the angle θ between the x-axis direction and themajor-axis direction of each liquid crystal molecule 30 is about 0°. Theliquid crystal alignment direction is induced in such a manner in orderto increase the maximum transmittance of a liquid crystal display.

The polarizing plate 1 and the polarizing plate 8 can be adjusted sothat a satisfactory viewing angle and a high contrast are achieved byadjusting the polarization axis of each of the polarizing plates. Thepolarizing plate 1 and the polarizing plate 8 preferably havetransmission axes that are perpendicular to each other so that a displaydevice is operated in a normally black mode. In particular, one of thepolarizing plate 1 and the polarizing plate 8 is preferably disposed soas to have a transmission axis parallel to the alignment direction ofthe liquid crystal molecules 30. The product of the refractive indexanisotropy Δn of the liquid crystal and the cell thickness d ispreferably adjusted so that the contrast is maximized. Furthermore, aphase difference film may be used to increase the viewing angle.

In the FFS mode liquid crystal display 10 having the above structure, animage signal (voltage) is supplied to the pixel electrode 21 through thethin film TFT to generate a fringing field between the pixel electrode21 and the common electrode 22, and liquid crystal is driven by thefringing field. That is, when no voltage is applied, the liquid crystalmolecules 30 are arranged so that the major-axis direction is parallelto the alignment direction of the alignment films 4. When a voltage isapplied, an equipotential line of a parabolic electric field is formedbetween the pixel electrode 21 and an upper portion of the commonelectrode 22, thereby rotating the liquid crystal molecules 30 in theliquid crystal layer 5 along the formed electric field. In the presentinvention, since the liquid crystal molecules 30 have a negativedielectric anisotropy, the liquid crystal molecules 30 rotate so thatthe major-axis direction of the liquid crystal molecules 30 isperpendicular to the direction of the generated electric field. Theliquid crystal molecules 30 located near the pixel electrode 21 areeasily affected by the fringing field. However, the polarizationdirection of the liquid crystal molecules 30 having a negativedielectric anisotropy is a minor-axis direction of the molecules, andthus the major-axis direction of the molecules does not rotate to adirection perpendicular to the alignment films 4. As a result, themajor-axis direction of all the liquid crystal molecules 30 in theliquid crystal layer 5 remains in a direction parallel to the alignmentfilms 4. Accordingly, a high transmittance can be achieved compared withan FFS mode liquid crystal display device including liquid crystalmolecules 30 having a positive dielectric anisotropy.

The FFS mode liquid crystal display device described with reference toFIGS. 1 to 4 is merely an example, and various modifications can be madewithout departing from the technical ideas of the present invention. Forexample, FIG. 5 shows another example of an enlarged plan view of aregion of the electrode layer 3 formed on the substrate 2 in FIG. 1, theregion being enclosed by line II. As shown in FIG. 5, the pixelelectrode 21 may have slits. The slits may be formed so as to have anangle of inclination relative to the gate bus lines 26 or the data buslines 25.

FIG. 6 shows another example of a sectional view of the liquid crystaldisplay device shown in FIG. 1, the sectional view being taken alongline III-III in FIG. 2. In the example shown in FIG. 6, a comb-shapedcommon electrode 22 or a common electrode 22 having slits is used, andthe interelectrode distance R between the pixel electrode 21 and thecommon electrode 22 is a. Although FIG. 3 shows an example in which thecommon electrode 22 is formed on the gate insulating layer 12, thecommon electrode 22 may be formed on the first substrate 2 and the pixelelectrode 21 may be formed thereon with the gate insulating layer 12disposed therebetween as shown in FIG. 6. The electrode width 1 of thepixel electrode 21, the electrode width n of the common electrode 22,and the interelectrode distance R are preferably suitably adjusted insuch a manner that all liquid crystal molecules in the liquid crystallayer 5 are driven by the generated electric field.

Since the FFS mode liquid crystal display device according to thepresent invention includes a particular liquid crystal composition, bothhigh-speed response and the suppression of display defects can beachieved.

In FFS mode liquid crystal display devices, the liquid crystal layer 5is injected between the first substrate 2 and the second substrate 7 by,for example, a vacuum injection method or a one-drop-fill (ODF) method.In the present invention, the generation of drop marks formed when aliquid crystal composition is dropped onto a substrate can be suppressedin the ODF method. The drop marks are defined as a phenomenon in which amark formed by dropping a liquid crystal composition appears white on ablack screen.

The generation of drop marks is considerably affected by an injectedliquid crystal material and also inevitably affected by the structure ofthe display device. In FFS mode liquid crystal display devices, the thinfilm transistor, the comb-shaped pixel electrode 21 or the pixelelectrode 21 having slits, and the like formed in the display device arehighly likely to contact an ionic substance because only the thinalignment films 4 or only the thin alignment films 4 and the thininsulating protective layer 18 are members that block the liquid crystalcomposition. As a result, the generation of drop marks formed by theinteraction between a metal material constituting the electrode and theliquid crystal composition cannot be avoided. However, the generation ofdrop marks is effectively suppressed by combining the FFS mode liquidcrystal display devices with the liquid crystal composition of thepresent invention.

In the production process of liquid crystal display devices by the ODFmethod, an optimum amount of liquid crystal injected needs to be droppedin accordance with the size of a liquid crystal display device. Theliquid crystal composition according to the present invention is lessaffected by a sudden change in pressure in a dropping device and animpact that occur when liquid crystal is dropped and thus the liquidcrystal can be continuously dropped in a stable manner for a long time.Therefore, a high production yield of the liquid crystal display devicecan be maintained. In particular, in small-size liquid crystal displaydevices heavily used for fashionable smart phones, the optimum amount ofliquid crystal injected is small and thus it is difficult to control thedeviation from the optimum amount within a particular range. However, byusing the liquid crystal composition according to the present invention,the amount of a liquid crystal material ejected can be stably maintainedeven in small-size liquid crystal display devices.

EXAMPLES

The present invention will now be further described below in detailbased on Examples, but is not limited to Examples. In the compositionsof Examples and Comparative Examples below, “%” means “mass %”.

The properties that were measured in Examples are as follows.

T_(NI): nematic phase-isotropic liquid phase transition temperature (°C.)

Δn: refractive index anisotropy at 25° C.

Δ∈: dielectric anisotropy at 25° C.

η: viscosity (mPa·s) at 20° C.

γ₁: rotational viscosity (mPa·s) at 25° C.

VHR: voltage holding ratio (%) at a frequency of 60 Hz at an appliedvoltage of 1 V at 60° C.

Image Sticking:

Image sticking evaluation for the liquid crystal display device wasperformed by performing uniform display on the entire screen afterdisplaying a particular fixed pattern in a display area for 1000 hours,and visually evaluating the degree of the afterimage of the fixedpattern on the basis of the four-grade evaluation below.

A: No afterimage was observed.

B: Faint afterimage was observed but the degree of the afterimage wasacceptable.

C: Afterimage was observed and the degree of the afterimage wasunacceptable.

D: Very poor afterimage was observed.

Drop Mark:

Drop mark evaluation for the liquid crystal display device was performedby visually evaluating a drop mark that appeared white on a black screenon the basis of the four-grade evaluation below.

A: No afterimage was observed.

B: Faint afterimage was observed but the degree of the afterimage wasacceptable.

C: Afterimage was observed and the degree of the afterimage wasunacceptable.

D: Very poor afterimage was observed.

Process Compatibility:

Liquid crystal was dropped 100,000 times at 50 pL per dropping using aconstant volume pump in an ODF process, and the changes in the amount ofliquid crystal dropped for every 100 droppings, namely, “0 to 100thdropping, 101st to 200th dropping, 201st to 300th dropping, . . .99901st to 100000th dropping”, were evaluated on the basis of thefollowing four grades.

A: Very little change was observed (liquid crystal display devices canbe stably produced).

B: Slight change was observed but the degree thereof was acceptable.

C: The degree of change was unacceptable (yield was degraded due togeneration of nonuniformity).

D: Considerable change was observed (liquid crystal leakage and vacuumbubbles occurred).

Solubility at Low Temperature:

The solubility at low temperature was evaluated as follows. After aliquid crystal composition was prepared, 1 g of the liquid crystalcomposition was weighed and placed in a 2 mL sample bottle. Theresulting sample was continuously exposed to temperature change cycles,each cycle including “−20° C. (retained for 1 hour)→heating (0.1°C./min)→0° C. (retained for 1 hour)→heating (0.1° C./min)→20° C.(retained for 1 hour)→cooling (−0.1° C./min)→0° C. (retained for 1hour)→cooling (−0.1° C./min)→−20° C.”, in a temperature control testchamber. Generation of precipitates from the liquid crystal compositionwas visually observed and the following four-grade evaluation wasperformed.

A: No precipitates were observed for 600 hours or longer.

B: No precipitates were observed for 300 hours or longer.

C: Precipitates were observed within 150 hours.

D: Precipitates were observed within 75 hours.

In Examples, the following abbreviations are used to describe compounds.

(Side Chain)

-n: —CnH2n+1, linear alkyl group having n carbon atoms

—On: —OCnH2n+1, linear alkoxy group having n carbon atoms

—V: —C═CH2, vinyl group

—Vn: —C═C—CnH2n+1, 1-alkene having (n+1) carbon atoms

(Ring Structure)

Example 1 Liquid Crystal Composition 1

A liquid crystal composition (liquid crystal composition 1) having acomposition below was prepared and the physical properties of thecomposition were measured. The results are shown in Table 1.

An FFS mode liquid crystal display device having a cell thickness of 3.0μm, which is typically used for TVs, was produced using the liquidcrystal composition 1. The liquid crystal composition was injected by adropping method and the image sticking, the drop mark, the processcompatibility, and the solubility at low temperature were evaluated.

Note that the symbols on the left of the content are abbreviateddescriptions of the above compounds.

3CyCyV 31%

3CyCyV1 11%

3CyPh5O2 13%

5CyPh5O2  6%

3CyCyPh5O2 11%

2CyPhPh5O2  5%

3CyPhPh5O2 10%

3PhPh5Ph2 13%

Example 1

TABLE 1 T_(NI)/° C. 75.6 Δn 0.109 n_(o) 1.483 Δε −3.07 ε_(⊥) 6.62 η/mPa· s 15.2 γ₁/mPa · s 98 γ1/Δn2 × 10³ 8.2 γ1/Δn2/|Δε| 2.69 Initial voltageholding ratio/% 99.6 Voltage holding ratio after 150° C. and 1 h/% 99.0Evaluation of image sticking A Evaluation of drop mark A Evaluation ofprocess compatibility A Evaluation of solubility at low temperature A

The liquid crystal composition 1 is found to have a T_(NI) of 75.6° C.,which is practical for liquid crystal compositions for TVs, a highabsolute value of Δ∈, low η, and appropriate Δn. An FFS mode liquidcrystal display device was produced using the liquid crystal composition1 and the image sticking, the drop mark, the process compatibility, andthe solubility at low temperature were evaluated by the above-describedmethods. The evaluation results were excellent.

Example 2 Liquid Crystal Composition 2

A liquid crystal composition (liquid crystal composition 2) having acomposition below and designed so as to have the same T_(NI), Δn, and Δ∈as those of the liquid crystal composition 1 was prepared, and thephysical properties were measured. The results are shown in Table 2.

An FFS mode liquid crystal display device was produced using the liquidcrystal composition 2 in the same manner as in Example 1. The imagesticking, the drop mark, the process compatibility, and the solubilityat low temperature were evaluated. The results are shown in Table 2.

TABLE 2 3CyCyV 32%  3CyCyV1 12%  3CyCyPh1 4% 3CyPh5O2 7% 3PhPh5O2 10% 3CyCyPh5O2 10%  4CyCyPh5O2 2% 2CyPhPh5O2 5% 3CyPhPh5O2 8% 3PhPh5Ph2 5%4PhPh5Ph2 5% T_(NI)/° C. 76.6 Δn 0.110 n_(o) 1.485 Δε −3.03 ε_(⊥) 6.36η/mPa · s 13.6 γ₁/mPa · s 90 γ1/Δn² × 10⁻³ 7.4 γ₁/Δn²/|Δε| 2.45 Initialvoltage holding ratio/% 99.5 Voltage holding ratio after 150° C. and 1h/% 99.0 Evaluation of image sticking A Evaluation of drop mark AEvaluation of process compatibility A Evaluation of solubility at lowtemperature A

Example 2

The liquid crystal composition 2 is found to have a liquid crystal phasetemperature range which is practical for liquid crystal compositions forTVs, a high absolute value of dielectric anisotropy, a low viscosity,and appropriate Δn. The same FFS mode liquid crystal display device asin Example 1 was produced using the liquid crystal composition 2 and theimage sticking, the drop mark, the process compatibility, and thesolubility at low temperature were evaluated by the above-describedmethods. The evaluation results were excellent.

Example 3 Liquid Crystal Composition 3

A liquid crystal composition (liquid crystal composition 3) having acomposition below and designed so as to have the same T_(NI), Δn, and Δ∈as those of the liquid crystal compositions 1 and 2 was prepared, andthe physical properties were measured. The results are shown in Table 3.

An FFS mode liquid crystal display device was produced using the liquidcrystal composition 3 in the same manner as in Example 1. The imagesticking, the drop mark, the process compatibility, and the solubilityat low temperature were evaluated. The results are shown in Table 3.

TABLE 3 3CyCyV 35% 3CyCyV1 12% 3CyCyPh1  2% 3CyPhPh2  6% 3CyPh5O2  4%3PhPh5O2 10% 5PhPh5O2  4% 3CyCyPh5O2  3% 2CyPhPh5O2 12% 3CyPhPh5O2 12%T_(NI)/° C. 76.1 Δn 0.110 n_(o) 1.486 Δε −3.09 ε_(⊥) 6.45 η/mPa · s 12.2γ₁/mPa · s 81 γ1/Δn² × 10⁻³ 6.7 γ₁/Δn²/|Δε| 2.17 Initial voltage holdingratio/% 99.6 Voltage holding ratio after 150° C. and 1 h/% 99.2Evaluation of image sticking A Evaluation of drop mark A Evaluation ofprocess compatibility A Evaluation of solubility at low temperature A

Example 3

The liquid crystal composition 3 is found to have T_(NI) which ispractical for liquid crystal compositions for TVs, a high absolute valueof Δ∈, low η, and appropriate Δn. The same FFS mode liquid crystaldisplay device as in Example 1 was produced using the liquid crystalcomposition 3 and the image sticking, the drop mark, the processcompatibility, and the solubility at low temperature were evaluated bythe above-described methods. The evaluation results were excellent.

Comparative Examples 1 to 3

Vertical alignment mode liquid crystal display devices (VA mode liquidcrystal display devices) having a cell thickness of 3.5 μm, which aretypically used for TVs, were produced using the liquid crystalcompositions 1 to 3.

The FFS mode liquid crystal display devices produced in Examples 1 to 3and the VA mode liquid crystal display devices produced in ComparativeExamples 1 to 3 were compared with each other in terms of transmittance,contrast ratio, and response speed. The results are shown below. Thetransmittance of the liquid crystal display devices in Examples 1 to 3is a value obtained when the transmittance of the FFS mode devicesbefore injection of the liquid crystal compositions is assumed to be100%. The transmittance of the liquid crystal display devices inComparative Examples 1 to 3 is a value obtained when the transmittanceof the VA mode devices before injection of the liquid crystalcompositions is assumed to be 100%.

TABLE 4 Comparative Comparative Comparative Example 1 Example 1 Example2 Example 2 Example 3 Example 3 Display mode n-FFS VA n-FFS VA n-FFS VALiquid crystal Liquid crystal Liquid crystal Liquid crystal compositionused composition 1 composition 2 composition 3 Maximum 89% 87% 90% 86%90% 87% transmittance Contrast ratio 289 280 293 277 302 288 Responsespeed/ms 4.7 8.3 4.4 7.6 3.7 6.6

The FFS mode display devices (Examples 1 to 3) produced using the liquidcrystal compositions 1 to 3 had better properties than the VA modeliquid crystal display devices (Comparative Examples 1 to 3) producedusing the same liquid crystal compositions in terms of maximumtransmittance, contrast ratio, and response speed.

The FFS mode liquid crystal display device in which liquid crystalmolecules are aligned in a direction parallel to the substrate and afringing field is generated needs to have basic properties of liquidcrystal different from those of the VA mode liquid crystal displaydevice in which liquid crystal molecules are aligned in a directionperpendicular to the substrate and an electric field is verticallygenerated. The liquid crystal compositions 1 to 3 contain the compoundsrepresented by the general formula (I) and the general formula (II),which are essential components in the present invention. Therefore, animprovement in transmittance, which is a distinctive characteristic ofthe FFS mode, is achieved without impairing the basic properties of aliquid crystal display device. However, because of such a differencebetween the FFS mode and the VA mode, it is difficult to predict theeffects on the image sticking and drop marks from the previous findings.The liquid crystal display devices of the present invention exhibit goodproperties in these points.

Example 4 Liquid Crystal Composition 4

A liquid crystal composition (liquid crystal composition 4) having acomposition below and designed so as to have the same T_(NI), Δn, and Δ∈as those of the liquid crystal compositions 1 to 3 was prepared, and thephysical properties were measured. The results are shown in Table 5.

TABLE 5 3CyCy2 25% 3CyCy4  8% 3CyCy5  5% 3CyPh5O2 10% 5CyPh5O2  9%3CyCyPh5O2 11% 2CyPhPh5O2 10% 3CyPhPh5O2 11% 3PhPh5Ph2  5% 4PhPh5Ph2  6%T_(NI)/° C. 75.9 Δn 0.104 n_(o) 1.483 Δε −3.06 ε_(⊥) 6.56 η/mPa · s 19.9γ₁/mPa · s 137 γ1/Δn² × 10⁻³ 12.7 γ₁/Δn²/|Δε| 4.14

Example 4

The liquid crystal composition 4 is found to have T_(NI) which ispractical for liquid crystal compositions for TVs, a high absolute valueof Δ∈, low η, and appropriate Δn. An FFS mode liquid crystal displaydevice produced using the liquid crystal composition 4 exhibited as gooddisplay properties as those of Examples 1 to 3.

Example 5 Liquid Crystal Composition 5

A liquid crystal composition (liquid crystal composition 5) having acomposition below and designed so as to have the same T_(NI), Δn, and Δ∈as those of the liquid crystal compositions 1 to 4 was prepared, and thephysical properties were measured. The results are shown in Table 6.

TABLE 6 3CyCy2 25%  3CyCy4 10%  3CyCy5 5% 3CyPh5O2 8% 3PhPh5O2 9%3CyCyPh5O2 12%  4CyCyPh5O2 2% 2CyPhPh5O2 9% 3CyPhPh5O2 9% 3PhPh5Ph2 5%4PhPh5Ph2 6% T_(NI)/° C. 75.8 Δn 0.108 n_(o) 1.485 Δε −3.17 ε_(⊥) 6.53η/mPa · s 18.5 γ₁/mPa · s 131 γ1/Δn² × 10⁻³ 11.2 γ₁/Δn²/|Δε| 3.54

Example 5

The liquid crystal composition 5 is found to have T_(NI) which ispractical for liquid crystal compositions for TVs, a high absolute valueof Δ∈, low η, and appropriate Δn. An FFS mode liquid crystal displaydevice produced using the liquid crystal composition 5 exhibited as gooddisplay properties as those of Examples 1 to 3.

Example 6 Liquid Crystal Composition 6

A liquid crystal composition (liquid crystal composition 6) having acomposition below and designed so as to have the same T_(NI), Δn, and Δ∈as those of the liquid crystal compositions 1 to 5 was prepared, and thephysical properties were measured. The results are shown in Table 7.

TABLE 7 3CyCy2 25% 3CyCy4 10% 3CyCy5  6% 3CyCyPh1 10% 3CyPh5O2  5%3PhPh5O2 10% 5PhPh5O2  4% 3CyCyPh5O2  6% 2CyPhPh5O2 12% 3CyPhPh5O2 12%T_(NI)/° C. 78.1 Δn 0.101 n_(o) 1.484 Δε −3.00 ε_(⊥) 6.22 η/mPa · s 15.9γ₁/mPa · s 111 γ1/Δn² × 10⁻³ 10.9 γ₁/Δn²/|Δε| 3.63

Example 6

The liquid crystal composition 6 is found to have T_(NI) which ispractical for liquid crystal compositions for TVs, a high absolute valueof Δ∈, low η, and appropriate Δn. An FFS mode liquid crystal displaydevice produced using the liquid crystal composition 6 exhibited as gooddisplay properties as those of Examples 1 to 3.

Example 7 Liquid Crystal Composition 7

A liquid crystal composition (liquid crystal composition 7) having acomposition below and designed so as to have the same Δn as that of theliquid crystal compositions 1 to 6 and higher T_(NI) and Δ∈ than theliquid crystal compositions 1 to 6 was prepared, and the physicalproperties were measured. The results are shown in Table 8.

TABLE 8 3CyCyV 24% 3CyCyV1 10% 3CyPh5O2 12% 5CyPh5O2  8% 3CyCyPh5O2 10%3CyCyPh5O3  8% 4CyCyPh5O2 10% 2CyPhPh5O2  5% 3CyPhPh5O2  5% 3PhPh5Ph2 8% T_(NI)/° C. 86.0 Δn 0.103 n_(o) 1.481 Δε −3.95 ε_(⊥) 7.76 η/mPa · s21.8 γ₁/mPa · s 134 γ1/Δn² × 10⁻³ 12.6 γ₁/Δn²/|Δε| 3.20 Initial voltageholding ratio/% 99.9 Voltage holding ratio after 150° C. and 1 h/% 99.4Evaluation of image sticking A Evaluation of drop mark A Evaluation ofprocess compatibility A Evaluation of solubility at low temperature A

Example 7

The liquid crystal composition 7 is found to have T_(NI) which ispractical for liquid crystal compositions for TVs, a high absolute valueof Δ∈, low η, and appropriate Δn. The same FFS mode liquid crystaldisplay device as in Example 1 was produced using the liquid crystalcomposition 7 and the image sticking, the drop mark, the processcompatibility, and the solubility at low temperature were evaluated bythe above-described methods. The evaluation results were excellent.

Example 8 Liquid Crystal Composition 8

A liquid crystal composition (liquid crystal composition 8) having acomposition below and designed so as to have the same T_(NI), Δn, and Δ∈as those of the liquid crystal composition 7 was prepared, and thephysical properties were measured. The results are shown in Table 9.

TABLE 9 3CyCyV 20%  3CyCyV1 10%  3CyCyPh1 7% 3CyPh5O2 12%  5CyPh5O2 6%3PhPh5O2 5% 3CyCyPh5O2 12%  3CyCyPh5O3 6% 4CyCyPh5O2 10%  2CyPhPh5O2 6%3PhPh5Ph2 6% T_(NI)/° C. 85.6 Δn 0.103 n_(o) 1.482 Δε −4.05 ε_(⊥) 7.74η/mPa · s 21.2 γ₁/mPa · s 128 γ1/Δn² × 10⁻³ 12.1 γ₁/Δn²/|Δε| 2.98Initial voltage holding ratio/% 99.9 Voltage holding ratio after 150° C.and 1 h/% 99.5 Evaluation of image sticking A Evaluation of drop mark AEvaluation of process compatibility A Evaluation of solubility at lowtemperature A

Example 8

The liquid crystal composition 8 is found to have T_(NI) which ispractical for liquid crystal compositions for TVs, a high absolute valueof Δ∈, low η, and appropriate Δn. The same FFS mode liquid crystaldisplay device as in Example 1 was produced using the liquid crystalcomposition 8 and the image sticking, the drop mark, the processcompatibility, and the solubility at low temperature were evaluated bythe above-described methods. The evaluation results were excellent.

Example 9 Liquid Crystal Composition 9

A liquid crystal composition (liquid crystal composition 9) having acomposition below and designed so as to have the same T_(NI), Δn, and Δ∈as those of the liquid crystal compositions 7 and 8 was prepared, andthe physical properties were measured. The results are shown in Table10.

TABLE 10 3CyCyV 23% 3CyCyV1 10% 3CyCyPh1 10% 3CyPh5O2 10% 5CyPh5O2  4%3PhPh5O2  8% 3CyCyPh5O2 12% 4CyCyPh5O2  7% 2CyPhPh5O2  8% 3CyPhPh5O2  8%T_(NI)/° C. 86.2 Δn 0.103 n_(o) 1.483 Δε −3.96 ε_(⊥) 7.56 η/mPa · s 18.7γ₁/mPa · s 112 γ1/Δn² × 10⁻³ 10.6 γ₁/Δn²/|Δε| 2.67 Initial voltageholding ratio/% 99.8 Voltage holding ratio after 150° C. and 1 h/% 99.3Evaluation of image sticking A Evaluation of drop mark A Evaluation ofprocess compatibility A Evaluation of solubility at low temperature A

Example 9

The liquid crystal composition 9 is found to have T_(NI) which ispractical for liquid crystal compositions for TVs, a high absolute valueof Δ∈, low η, and appropriate Δn. The same FFS mode liquid crystaldisplay device as in Example 1 was produced using the liquid crystalcomposition 9 and the image sticking, the drop mark, the processcompatibility, and the solubility at low temperature were evaluated bythe above-described methods. The evaluation results were excellent.

Comparative Examples 4 to 6

The same VA mode liquid crystal display devices as in ComparativeExamples 1 to 3 were produced using the liquid crystal compositions 7 to9.

The FFS mode liquid crystal display devices produced in Examples 7 to 9and the VA mode liquid crystal display devices produced in ComparativeExamples 4 to 6 were compared with each other in terms of transmittance,contrast ratio, and response speed. The results are shown in Table 11.

TABLE 11 Comparative Comparative Comparative Example 7 Example 4 Example8 Example 5 Example 9 Example 6 Display mode n-FFS VA n-FFS VA n-FFS VALiquid crystal Liquid crystal Liquid crystal Liquid crystal compositionused composition 7 composition 8 composition 9 Maximum 88% 85% 88% 86%89% 87% transmittance/% Contrast ratio 278 268 285 265 294 260 Responsespeed/ms 7.4 13.0 7.1 12.7 6.5 10.8

The FFS mode display devices (Examples 7 to 9) produced using the liquidcrystal compositions 7 to 9 had better properties than the VA modeliquid crystal display devices (Comparative Examples 4 to 6) producedusing the same liquid crystal compositions in terms of maximumtransmittance, contrast ratio, and response speed.

Example 10 Liquid Crystal Composition 10

A liquid crystal composition (liquid crystal composition 10) having acomposition below and designed so as to have the same T_(NI), Δn, and Δ∈as those of the liquid crystal compositions 7 to 9 was prepared, and thephysical properties were measured. The results are shown in Table 12.

TABLE 12 3CyCy2 22%  3CyCy4 4% 3CyCyPh1 4% 3CyPh5O2 12%  5CyPh5O2 10% 3CyCyPh5O2 10%  3CyCyPh5O3 6% 4CyCyPh5O2 9% 2CyPhPh5O2 8% 3CyPhPh5O2 8%3PhPh5Ph2 4% 4PhPh5Ph2 3% T_(NI)/° C. 85.7 Δn 0.103 n_(o) 1.482 Δε −4.08ε_(⊥) 7.92 η/mPa · s 26.6 γ₁/mPa · s 172 γ1/Δn² × 10⁻³ 16.2 γ₁/Δn²/|Δε|3.97

Example 10

The liquid crystal composition 10 is found to have T_(NI) which ispractical for liquid crystal compositions for TVs, a high absolute valueof Δ∈, low η, and appropriate Δn. An FFS mode liquid crystal displaydevice was produced using the liquid crystal composition 10 and theimage sticking, the drop mark, the process compatibility, and thesolubility at low temperature were evaluated by the above-describedmethods. The evaluation results were excellent.

Example 11 Liquid Crystal Composition 11

A liquid crystal composition having a composition below and designed soas to have the same T_(NI), Δn, and Δ∈ as those of the liquid crystalcompositions 7 to 10 was prepared, and the physical properties weremeasured. The results are shown in Table 13.

TABLE 13 3CyCy2 24%  3CyCy4 8% 3CyPh5O2 9% 3PhPh5O2 8% 3CyCyPh5O2 12% 3CyCyPh5O3 10%  4CyCyPh5O2 10%  2CyPhPh5O2 6% 3CyPhPh5O2 6% 3PhPh5Ph2 4%4PhPh5Ph2 3% T_(NI)/° C. 86.0 Δn 0.103 n_(o) 1.483 Δε −4.03 ε_(⊥) 7.67η/mPa · s 24.3 γ₁/mPa · s 164 γ1/Δn² × 10⁻³ 15.5 γ₁/Δn²/|Δε| 3.84

Example 11

The liquid crystal composition 11 is found to have T_(NI) which ispractical for liquid crystal compositions for TVs, a high absolute valueof Δ∈, low η, and appropriate Δn. An FFS mode liquid crystal displaydevice was produced using the liquid crystal composition 11 and theimage sticking, the drop mark, the process compatibility, and thesolubility at low temperature were evaluated by the above-describedmethods. The evaluation results were excellent.

Example 12 Liquid Crystal Composition 12

A liquid crystal composition (liquid crystal composition 12) having acomposition below and designed so as to have the same T_(NI), Δn, and Δ∈as those of the liquid crystal compositions 7 to 11 was prepared, andthe physical properties were measured. The results are shown in Table14.

TABLE 14 3CyCy2 24% 3CyCy4  5% 3CyCyPh1  9% 3CyPh5O2 10% 5CyPh5O2  3%3PhPh5O2  8% 3CyCyPh5O2 10% 4CyCyPh5O2  9% 2CyPhPh5O2 11% 3CyPhPh5O2 11%T_(NI)/° C. 86.0 Δn 0.103 n_(o) 1.484 Δε −4.03 ε_(⊥) 7.69 η/mPa · s 22.5γ₁/mPa · s 145 γ1/Δn² × 10⁻³ 13.7 γ₁/Δn²/|Δε| 3.39

Example 12

The liquid crystal composition 12 is found to have T_(NI) which ispractical for liquid crystal compositions for TVs, a high absolute valueof Δ∈, low η, and appropriate Δn. An FFS mode liquid crystal displaydevice was produced using the liquid crystal composition 12 and theimage sticking, the drop mark, the process compatibility, and thesolubility at low temperature were evaluated by the above-describedmethods. The evaluation results were excellent.

Example 13 Liquid Crystal Composition 13

A liquid crystal composition (liquid crystal composition 13) having acomposition below and designed so as to have the same T_(NI), Δn, and Δ∈as those of the liquid crystal compositions 7 to 12 was prepared, andthe physical properties were measured. The results are shown in Table15.

TABLE 15 3CyCyV 20% 3CyCyV1 10% 3CyCyPh1  7% 3CyPhPh2  3% 3CyPh5O2 13%5CyPh5O2 12% 3CyCyPh5O2 10% 4CyCyPh5O2  5% 2CyPhPh5O2 10% 3CyPhPh5O2 10%T_(NI)/° C. 85.8 Δn 0.103 n_(o) 1.482 Δε −4.02 ε_(⊥) 7.82 η/mPa · s 20.9γ₁/mPa · s 123 γ1/Δn² × 10⁻³ 11.6 γ₁/Δn²/|Δε| 2.88

Example 13

The liquid crystal composition 13 is found to have T_(NI) which ispractical for liquid crystal compositions for TVs, a high absolute valueof Δ∈, low η, and appropriate Δn. The same FFS mode liquid crystaldisplay device as in Example 1 was produced using the liquid crystalcomposition 13 and the image sticking, the drop mark, the processcompatibility, and the solubility at low temperature were evaluated bythe above-described methods. The evaluation results were excellent.

Example 14 Liquid Crystal Composition 14

A liquid crystal composition (liquid crystal composition 14) having acomposition below and designed so as to have the same T_(NI), Δn, and Δ∈as those of the liquid crystal compositions 7 to 13 was prepared, andthe physical properties were measured. The results are shown in Table16.

TABLE 16 3CyCy2 22% 3CyCy4  3% 3CyCyPh1  7% 3CyCyPh2  4% 3CyPh5O2 13%5CyPh5O2 12% 3CyCyPh5O2  9% 4CyCyPh5O2  6% 2CyPhPh5O2 12% 3CyPhPh5O2 12%T_(NI)/° C. 85.0 Δn 0.103 n_(o) 1.483 Δε −4.04 ε_(⊥) 7.88 η/mPa · s 24.3γ₁/mPa · s 152 γ1/Δn² × 10⁻³ 14.3 γ₁/Δn²/|Δε| 3.55

Example 14

The liquid crystal composition 14 is found to have T_(NI) which ispractical for liquid crystal compositions for TVs, a high absolute valueof Δ∈, low η, and appropriate Δn. The same FFS mode liquid crystaldisplay device as in Example 1 was produced using the liquid crystalcomposition 14 and the image sticking, the drop mark, the processcompatibility, and the solubility at low temperature were evaluated bythe above-described methods. The evaluation results were excellent.

REFERENCE SIGNS LIST

-   -   1,8 polarizing plate    -   2 first substrate    -   3 electrode layer    -   4 alignment film    -   5 liquid crystal layer    -   6 color filter    -   7 second substrate    -   11 gate electrode    -   12 gate insulating layer    -   13 semiconductor layer    -   14 insulating layer    -   15 ohmic contact layer    -   16 drain electrode    -   17 source electrode    -   18 insulating protective layer    -   21 pixel electrode    -   22 common electrode    -   23 storage capacitor    -   25 data bus line    -   27 source bus line    -   29 common line

1. An FFS mode liquid crystal display device comprising a firsttransparent insulating substrate and a second transparent insulatingsubstrate disposed so as to face each other; a liquid crystal layercontaining a liquid crystal composition and sandwiched between the firsttransparent insulating substrate and the second transparent insulatingsubstrate; a common electrode composed of a transparent conductivematerial and disposed on the first transparent insulating substrate; aplurality of gate bus lines and a plurality of data bus lines disposedon the first transparent insulating substrate so as to form a matrix; athin film transistor disposed at each of intersections of the gate buslines and the data bus lines; a pixel electrode composed of atransparent conductive material and driven by the transistor, the thinfilm transistor and the pixel electrode being included in each pixel;and alignment films that induce homogeneous alignment and are disposedbetween the liquid crystal layer and the first transparent insulatingsubstrate and between the liquid crystal layer and the secondtransparent insulating substrate, alignment directions of the alignmentfilms being parallel to each other, wherein an interelectrode distance Rbetween the pixel electrode and the common electrode is smaller than adistance G between the first transparent insulating substrate and thesecond transparent insulating substrate so that a fringing field isformed between the pixel electrode and the common electrode, the commonelectrode is disposed on substantially an entire surface of the firsttransparent insulating substrate so as to be closer to the firsttransparent insulating substrate than the pixel electrode, and theliquid crystal composition has a negative dielectric anisotropy, anematic phase-isotropic liquid phase transition temperature of 60° C. orhigher, and an absolute value of dielectric anisotropy of 2 or more, theliquid crystal composition having a refractive index anisotropy Δn of0.10 or more, and the liquid crystal composition comprises: at least onecompound selected from the group of compounds represented by generalformula (I), at least one compound selected from the group of compoundsrepresented by general formula (II); and one or more of compoundsrepresented by general formula (IV),

wherein in the general formula (I), R¹ and R² each independentlyrepresent an alkyl group having 1 to 8 carbon atoms, an alkenyl grouphaving 2 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms,or an alkenyloxy group having 2 to 8 carbon atoms; A represents atrans-1,4-cyclohexylene group; k represents 1; and when k represents 2,two A may be the same or different),

wherein in the general formula (II), R³ represents an alkyl group having1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, analkoxy group having 1 to 8 carbon atoms, or an alkenyloxy group having 2to 8 carbon atoms; R⁴ represents an alkyl group having 1 to 8 carbonatoms, an alkenyl group having 4 to 8 carbon atoms, an alkoxy grouphaving 1 to 8 carbon atoms, or an alkenyloxy group having 3 to 8 carbonatoms; B represents a 1,4-phenylene group or a trans-1,4-cyclohexylenegroup; m represents 0, 1, or 2; and when m represents 2, two B may bethe same or different,

wherein the general formula (IV), R⁷ and R⁸ each independently representan alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or analkenyloxy group having 2 to 8 carbon atoms; one or more hydrogen atomsin the alkyl group, the alkenyl group, the alkoxy group, or thealkenyloxy group may be substituted with fluorine atoms; a methylenegroup in the alkyl group, the alkenyl group, the alkoxy group, or thealkenyloxy group may be substituted with an oxygen atom as long asoxygen atoms do not directly bond to each other and may be substitutedwith a carbonyl group as long as carbonyl groups do not directly bond toeach other; A¹ and A² each independently represent a 1,4-cyclohexylenegroup, a 1,4-phenylene group, or a tetrahydropyran-2,5-diyl group; whenA¹ and/or A² represents a 1,4-phenylene group, one or more hydrogenatoms in the 1,4-phenylene group may be substituted with fluorine atoms;Z¹ and Z² each independently represent a single bond, —OCH₂—, —OCF₂—,—CH₂O—, or CF₂O—; n¹ and n² each independently represent 0, 1, 2, or 3and n¹+n² is 1 to 3; when a plurality of A¹, A², Z¹, and/or Z² arepresent, A¹, A², Z¹, and/or Z² may be the same or different, wherein thegeneral formula (IV) excludes a compound in which n¹ represents 1 or 2,n² represents 0, A¹ represents a 1,4-cyclohexylene group, and all Z¹represent single bonds.
 2. The liquid crystal display device accordingto claim 1, wherein the compounds represented by the general formula (I)include at least one compound selected from the group of compoundsrepresented by general formula (III) below,

(in the formula, R⁵ represents a hydrogen atom or a methyl group and R⁶represents an alkyl group having 1 to 5 carbon atoms, an alkenyl grouphaving 2 to 5 carbon atoms, or an alkoxy group having 1 to 4 carbonatoms).
 3. The liquid crystal composition according to claim 1, whereinthe compounds represented by the general formula (IV) include at leastone compound selected from the group of compounds represented by generalformula (IVa1) and general formula (IVa2) below,

(in the formula, R^(7a1), R^(7a2), R^(8a1), and R^(8a2) eachindependently represent an alkyl group having 1 to 8 carbon atoms, analkenyl group having 2 to 8 carbon atoms, an alkoxy group having 1 to 8carbon atoms, or an alkenyloxy group having 2 to 8 carbon atoms; one ormore hydrogen atoms in the alkyl group, the alkenyl group, the alkoxygroup, or the alkenyloxy group may be substituted with fluorine atoms; amethylene group in the alkyl group, the alkenyl group, the alkoxy group,or the alkenyloxy group may be substituted with an oxygen atom as longas oxygen atoms do not directly bond to each other and may besubstituted with a carbonyl group as long as carbonyl groups do notdirectly bond to each other; n^(a2) represents 0 or 1; A^(1a2)represents a 1,4-cyclohexylene group, a 1,4-phenylene group, or atetrahydropyran-2,5-diyl group; and one or more hydrogen atoms in the1,4-phenylene group in the general formula (IVa1) and the generalformula (IVa2) may be substituted with fluorine atoms).
 4. The liquidcrystal display device according to claim 1, wherein the pixel electrodeis a comb-shaped pixel electrode or a pixel electrode having a slit. 5.The liquid crystal display device according to claim 1, wherein thetotal content of the compounds represented by the general formula (I),the general formula (II), and the general formula (IV) in the liquidcrystal composition is 90 to 100 mass %.
 6. The liquid crystal displaydevice according to claim 1, wherein the liquid crystal composition hasa refractive index anisotropy Δn of 0.10 to 0.12.
 7. The liquid crystaldisplay device according to claim 1 wherein the interelectrode distance(R) is
 0. 8. The liquid crystal display device according to claim 1wherein the total content of the compounds represented by the generalformula (I), the general formula (II), and the general formula (IV) inthe liquid crystal composition is 80 to 100 mass %.